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Renal diets in cats with chronic kidney disease

Clinical Scenario

Chloe, a 14 year old domestic shorthair cat, has just been diagnosed with IRIS late stage II kidney disease. She is not proteinuric and her blood pressure is normal. You have stabilised her azotaemia and her appetite is now good. What is the benefit of a kidney prescription diet for this cat?

3-Part Question (PICO)

In [cats with naturally occurring chronic kidney disease] does [a renal prescription diet compared to normal diet] increase the [survival time] of affected cats?

Search Strategy and Summary of Evidence

Search Strategy

MEDLINE(R) In-Process & Other Non-Indexed Citations and MEDLINE(R) 1946 to Present using the OVID interface

cat.mp. OR cats.mp. OR feline.mp. OR felines.mp. OR felis.mp. OR exp Cats/

AND

chronic renal failure.mp. OR chronic renal disease.mp. OR chronic renal insufficiency.mp. OR chronic kidney failure.mp. OR chronic kidney disease.mp. OR chronic kidney insufficiency.mp. OR exp Kidney Failure, Chronic/ OR exp Renal Insufficiency, Chronic/

AND

renal diet.mp. OR kidney diet.mp. OR prescription diet.mp. OR therapeutic diet.mp. OR exp Diet Therapy/

CAB Abstracts 1910 to Present using the OVID interface

cat.mp. OR cats.mp. OR feline.mp. OR felines.mp.OR felis.mp. OR exp cats/

AND

chronic renal failure.mp. OR chronic renal disease.mp. OR chronic renal insufficiency.mp. OR chronic kidney insufficiency.mp. OR chronic kidney failure.mp. OR chronic kidney disease.mp. OR exp renal failure/ OR exp kidney disease/

AND

renal diet.mp. OR kidney diet.mp. OR prescription diet.mp. OR therapeutic diet.mp. OR exp renal diets/

Search Outcome

MEDLINE

  • 14 papers found in MEDLINE search
  • 5 papers excluded as they don't meet the PICO question
  • 0 papers excluded as they are in a foreign language
  • 6 papers excluded as they are review articles/in vitro research/conference proceedings
  • 3 total relevant papers from MEDLINE

CAB Abstracts

  • 18 papers found in CAB search
  • 7 papers excluded as they don't meet the PICO question
  • 0 papers excluded as they are in a foreign language
  • 10 papers excluded as they are review articles/in vitro research/conference proceedings
  • 1 total relevant papers from CAB

Total relevant papers

3 relevant papers from both MEDLINE and CAB Abstracts

Summary of Evidence

Elliott et al. (2000)

Title:

Survival of cats with naturally occurring chronic renal failure: effect of dietary management

Patient group:

Cats with naturally occurring chronic renal failure, N=50

Study Type:

Cohort study

Outcomes:
  • Survival time to maximum of 3-6 years (end point not well defined)
  • General health status
  • Blood pressure
  • Biochemical parameters
  • Parathyroid hormone
  • Urinalysis
Key Results:
  • The median survival for the renal prescription diet was 633 days (338-950), and 264 days (190-535) for normal diet (p=0.0036).
  • 68.8% cats in the normal diet group died of end-stage renal failure compared to 47.6% in the renal diet group
  • No significant differences in creatinine between groups (no p value given)
  • Phosphate levels were significantly higher at the mid survival point in the cats on the normal diet when compared to the renal diet (p=0.008)
  • 10 cats needed phosphate binders in the renal diet group; not offered in the normal diet group
  • Potassium supplementation was required by 23.*% cats in the normal diet and 27.5% cats in the renal diet group

 

Study Weaknesses:
  • No power calculation was reported
  • Small sample size at the start of the study (n=29 on renal diet, n=21 on normal diet)
  • Renal patients not staged, all patients had to be azotaemic and poor urine concentrating ability
  • The formulation of the available renal diet changed towards the end of the study
  • Parathyroid hormone and phosphate were monitored and therapy adjusted for cats in the renal diet group but not in the normal diet group

 

Attachment:
No attachments.

Ross et al. (2006) America

Title:

Clinical evaluation of dietary modification for treatment of spontaneous chronic kidney disease in cats.

Patient group:

Client-owned cats with spontaneous stage 2 or 3 Chronic Kidney disease, N=45

Study Type:

Randomised controlled trial

Outcomes:
  • Survival to 2 year, ureamic crisis as the end point
  • Physical examination
  • Ocular examination
  • Body condition score
  • Biochemistry parameters (including ionised calcium)
  • Parathyroid hormone
  • Complete blood cell count
  • Blood gas analysis
  • Urinalysis
  • Urine culture
  • Blood pressure
Key Results:
  • 11/22 cats on normal diets died of renal disease and 0/23 cats on the renal diets died of renal disease.
  • Urea (p<0.001) and creatinine (p=0.08) were significantly higher, and HCO3 (p<0.001) was significantly lower, in the renal diet group
  • 4 cats in the renal diet group did not eat the diet
Study Weaknesses:
  • No power calculation was done to determine the optimal size of the study
  • Small sample size at the start of the study (n=22 on renal diet, n=23 on normal diet)
  • Only 30 cats remained in the study for the full 24 months
  • Urea (p=0.009) and creatinine (p=0.09) were significantly higher and HCO3 (p=0.009) significantly lower in the normal diet group compared to the renal diet group at the start of the study. This may affect the results, as the azotaemia was worse in the control group.

 

Attachment:
No attachments.

Harte et al. (1994) United Kingdom

Title:

Dietary management of naturally occurring chronic renal failure in cats.

Patient group:

Cats with chronic renal disease, N=35

Study Type:

Randomised controlled trial

Outcomes:
  • Renal survival to 24 weeks

  • Clinical signs
  • Bodyweight

  • Biochemistry parameters

  • Urinalysis
Key Results:
  • Bodyweight was maintained in the renal diet group but deteriorated in the control group.

  • All cats showed clinical deterioration, but ‘less apparent’ in the renal diet group.

  • PCV, Albumen and total protein increased in the renal diet group but fell in the control group.

  • Creatinine and urea increased in the control group and decreased in the renal diet group during the study. These difference were reported to be ‘significantly different'.
Study Weaknesses:
  • No power calculation was done to determine the optimal size of the study.

  • Small sample size at the start of the study (n=22 on renal diet, n=23 on normal diet)

  • No basic data provided before or after treatment allocation made

  • No p values given in the results, so not possible to assess if the groups were significantly different following treatment
Attachment:
No attachments.

Comments

The studies all use different definitions of chronic kdiney disease/failure and measure the cats' survival for different periods of time. The Elliot et al. study is a cohort study which is a weaker form of evidence than a randomised controlled trial when assessing a treatment effect. There was not enough detail in the report by Harte et al. to fully assess the quality of the study. The Harte et al. study was funded by Waltham Centre for Pet Nutrition whose parent company made the renal diet.

Other studies were found during the search using young cats with surgically induced renal failure. We deemed that the results of these studies were not applicable to cats with naturally occurring chronic renal failure, so they were excluded from the BET.

Bottom line

A renal diet will improve the survival time of a cat with chronic kidney disease.

Disclaimer

The BETs on this website are a summary of the evidence found on a topic and are not clinical guidelines. It is the responsibility of the individual veterinary surgeon to ensure appropriate decisions are made based on the specific circumstances of patients under their care, taking into account other factors such as local licensing regulations. Read small print

References

Elliot J, Rawlings JM, Markwell PJ, Barber PJ (2000) Survival of cats with naturally occurring chronic renal failure: effect of dietary management. Journal of Small Animal Practice 41: 235-242.

Ross SJ, Osborne CA, Kirk CA, Lowry SR, Koehler LA, Polzin DJ (2006) Clinical evaluation of dietary modification for treatment of spontaneous chronic kidney disease in cats. Journal of the American Veterinary Medical Association 229: 949-957.

Harte JG, Markwell PJ, Moraillon RM, Gettinby GG, Smith BH, Wills JM (1994) Dietary management of naturally occurring chronic renal failure in cats. Journal of Nutrition 124: 2660S-2662S.

About this BET

First author:
Rachel Dean
Second author:
Martin Downes
Institution:

CEVM, University of Nottingham

Search last performed:
2016-03-01 08:48:03
Original publication date:
2013-09-13 08:48:03
Last updated:
2016-03-01 08:48:03
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